Association Between Air Quality Index and Risk of Alopecia Areata: A Nationwide Population-Based Cohort Study

This nationwide population-based cohort study in Taiwan investigated the association between air quality index (AQI) and the incidence of alopecia areata (AA) among 21,727,991 participants. Over a decade (2008-2018), 61,637 new cases of AA were identified. The study found a significant positive association between higher AQI levels and increased risk of AA, with a dose-response relationship. Compared to the group with the best AQI (Q1), the risk of AA increased progressively in groups with worse AQI: Q2 (adjusted hazard ratio [aHR]: 1.44), Q3 (aHR: 3.47), and Q4 (aHR: 6.18). Additionally, each unit increase in AQI raised the risk of AA by 5%.